I haven't been on this site in YEARS. I still see that people ask pretty lame questions rather than searching as they're supposed to. Therefore I feel free to post my interrogatory. A friend wanted me to help him build up a 5G hatch. His ultimate goal is to AX the car. The plan was to mate a B20 bottom with the wiseco pistons I already have to an ITR head and tranny. That was the plan. While looking for a hatch he found one already completed. It's a '95 Si. These are the mods that matter right now: B18b1 bottom GSR head with edelbrock adj cam gears JR supercharger stock header stock Si exhaust no Cat GSR tranny Hondata S300 with all the appropriate sensors working the former owner tells me it has "after market" pistons, forged crank, ARP rod bolts, but stock rods and "aftermarket" cams. He says it's running 8 lbs of boost now but adding a CRV crank pulley would bring it up to 14 which it could handle safely. Ok...all that to ask this. The stock exhaust has to go. I already have a 4-2-1 step header that I intended to add to a NA B20. Since this one is boosted, what's the best options for a header and what's the proper exhaust pipe size which retains as much low-end torque as the little 1800cc can put out? I have no idea how to properly use the S300 and the Hondata site is woefully slim on any "instructions". I'd like to at least be able to see what's going on right now with the motor and make sure it's not running lean. As always, your expert tutelage is appreciated, your flaming is not.